Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. Figure \(\PageIndex{4}\): Differences in the relative strengths of cohesive and adhesive forces result in different meniscus shapes for mercury (left) and water (right) in glass tubes. Water has an upward meniscus, mercury has a downward meniscus. Why does Mercury have a convex meniscus in a tube? Surface tensions of several liquids are presented in Table \(\PageIndex{2}\). This occurs with water and a glass tube. A .gov website belongs to an official government organization in the United States. Science Photo Library (SPL) Thus, the meniscus will be of concave shape. A concave meniscus occurs when the molecules of the liquid are more strongly attracted to the container than to each other. 1550520. GB 340 7410 88. A meniscus is a phase boundary that has been curved because ofsurface tension. The meniscus is the curvature of a liquid's surface within a container, such as a graduated cylinder. So this is the glass right over here. The meniscus can be either concave or convex, depending on the surface tension of the liquid and its adhesion to the wall of the container. Helmenstine, Anne Marie, Ph.D. "How to Read a Meniscus in Chemistry." All of a sudden for, you know, a very brief moment it spill right over there. ends at the hydrogens." When mercury is kept in glass meniscus is? A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. form around the oxygens. Water meniscus is convex, mercury menisucs is concave A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. In fact, if you took a Chapter 11.3: Unique Properties of Liquids - Chemistry LibreTexts Mercury shows a convex meniscus (the centre is higher than the edges), because internal cohesive forces are stronger than the force between the glass wall and the metal. In a science class, this liquid is usually water or some sort of aqueous solution, and the column is usually a graduated cylinder or a pipet. The Different Meanings of Meniscus in Science. Why does water forms upward meniscus in glass tube but mercury forms a In most cases, menisci are concave due to molecules of liquids more strongly attracted to the walls of the tube than to each other. VAT no. Water, Alcohol and Mercury. 20.1 x 26.7 cm 7.9 x 10.5 in (300dpi . When water is confined in a glass tube, its meniscus (surface) has a concave shape because the water wets the glass and creeps up the side of the tube. This makes good sense, considering the shape of a meniscus. Meniscus is caused by surface tension. in our circulation system. So what you see going on here, that is called adhesion, adhesion. Many medical tests require drawing a small amount of blood, for example to determine the amount of glucose in someone with diabetes or the hematocrit level in an athlete. A meniscus is a phase boundary that has been curved because of surface tension . SCIENCE PHOTO LIBRARY. In the case of the meniscus, equilibrium between the surface energies of the gas, solid and liquid. would call that adhesion. Please contact your Account Manager if you have any query. hydrogen bonding to form and that's what kind of gives water all of these special properties. Click here. A small tube has a relatively large surface area for a given volume of blood, which results in larger (relative) attractive forces, allowing the blood to be drawn farther up the tube. and the container, also known as "wetting", encourages as much liquid
The various IMFs between identical molecules of a substance are examples of cohesive forces. Water forms drops on these surfaces because the cohesive forces within the drops are greater than the adhesive forces between the water and the plastic. And if we didn't have a polar container, if we didn't have a hydrophilic container, well then the thing might If the liquid molecules are strongly attracted to the tube molecules, the liquid creeps up the inside of the tube until the weight of the liquid and the adhesive forces are in balance. But it has some kinetic energy, remember these things are jostling around, they're bouncing around, For a convex meniscus, this is the uppermost or top point of the liquid. And let's say I take a glass tube, and the material matters. Option C is correct. There are no media in the current basket. reason why you also see the water a little bit higher there. has partial negative end. Surface tension of ethanol is one third that of water. To say, "Hey this is a meniscus." Direct link to haekele's post Capillary action occurs, , Posted 7 years ago. In a science class, this liquid is usually water or some sort of aqueous solution, and the column is usually a graduated cylinder or a pipet. Invent and record a hypothesis to explain why liquids like water have a concave meniscus in a glass vial whereas mercury has a convex meniscus in a glass vial. The mercury atoms are strongly attracted to each other by metallic bonds. This turns the meniscus in an upward direction. Direct link to levongalstyan98's post Most cloth towels are mad, Posted 7 years ago. molecule gets attracted to it because of its hydrogen bonds. First: the chemical composure of glass (Si and partially negative O), What would happen if you put salt water in it. When you talk about A convex meniscus (sometimes called a "backwards" meniscus) is produced when the molecules of the liquid are more strongly attracted to each other than to the container. something sticking to itself, we call that cohesion. gets knocked up here. Figure 11.4. Concave Meniscus: molecule could jump up here and stick to the glass there. A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. the Terms and Conditions. When water is confined in a glass tube, its meniscus (surface) has a concave shape because the water wets the glass and creeps up the side of the tube. And so that's interesting. It forms what looks like the upper portion of a sphere - a convex meniscus. There are no media in the current basket. just jump back down. Glass is polar. The water molecules are also attracted to each other, so large amounts of water are drawn up the cellulose fibers. Unit 7: Intermolecular and Intramolecular Forces in Action, { "7.1:_Surface_Tension,_Viscosity,_and_Capillary_Action_(Problems)" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.
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